Mozilla Thunderbird vs. Spark

Comparison of Mozilla Thunderbird and Spark
Real cost
	Mozilla Thunderbird A free, open-source client for any number of accounts, with strong privacy. It looks plainer than rivals. Swap this Tool Use Audacity instead	Spark A modern inbox that sorts what matters first. Your mail passes through the vendor's servers. Swap this Tool Use Audacity instead
Price	0 €	60 € per year
Payment	Free	Subscription
Trial	No trial	No trial
Free Tier	No free tier	Free plan with the core mail features
Open Source	Yes	No
Features and limits
Main Features	Unlimited mail accounts Calendar and contacts Add-ons Strong privacy settings Message filters and tags	Smart inbox that sorts mail by importance Snooze and send later Shared inboxes for teams Writing help Unified inbox
Limits	Setup of some accounts takes a few steps The design is plainer than rivals	Mail is processed on the vendor's servers The best features need a paid plan
Compatibility and trust
Supported Operating Systems	WindowsmacOS	WindowsmacOS
Verified on	3 Oct 2026	10 Sep 2026
Where to buy
Vendor	Go to vendor’s site: Mozilla Thunderbird (opens in a new tab) Free, open source.	Go to vendor’s site: Spark (opens in a new tab) Free plan; paid plan per year. Approximate list price in euros, check the vendor.

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